sphingosine-1-phosphate and Neuralgia

Topics: Animals; Humans; Lysophospholipids; Neuralgia; Sphingosine; Sphingosine-1-Phosphate Receptors

Triple-negative breast cancer (TNBC) is very aggressive with high metastatic and mortality rates and unfortunately, except for chemotherapy, there are few therapeutic options. The bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P) regulates numerous processes important for cancer progression, metastasis, and neuropathic pain. The pro-drug FTY720 (fingolimod, Gilenya) used to treat multiple sclerosis is phosphorylated in the body to a S1P mimic that binds to S1PRs, except S1PR2, and also acts as a functional antagonist of S1PR1. This review highlights current findings showing that FTY720 has multiple anti-cancer activities and simultaneously prevents formation and actions of S1P. Moreover, in mouse breast cancer models, treatment with FTY720 reduces tumor growth, metastasis, and enhances sensitivity of advanced and hormonal refractory breast cancer and TNBC to conventional therapies. We discuss recent studies demonstrating that neuropathic pain induced by the chemotherapeutic bortezomib is also greatly reduced by administration of clinically relevant doses of FTY720, likely by targeting S1PR1 on astrocytes. FTY720 also shows promising anticancer potential in pre-clinical studies and is FDA approved, thus we suggest in this review that further studies are needed to pave the way for fast-tracking approval of FTY720/fingolimod for enhancing chemotherapy effectiveness and reduction of painful neuropathies.

Topics: Bortezomib; Breast Neoplasms; Chemotherapy, Adjuvant; Female; Fingolimod Hydrochloride; Humans; Lysophospholipids; Neuralgia; Signal Transduction; Sphingosine; Triple Negative Breast Neoplasms

Neuropathic pain arises from injuries to the nervous system. It affects 20% of the adult US population and poses a major socioeconomic burden yet remains exceedingly difficult to treat. Current therapeutic approaches have limited efficacy and a large side effect profile that impedes their ability to treat neuropathic pain effectively. Preclinical research over the last 30 yr has established the critical role that pro-inflammatory neuro-immune cell interactions have in the development and maintenance of neuropathic pain arising from various etiologies. Pro-inflammatory neuro-immune cell interactions also underlie the development of adverse side effects of opioids and the loss of their efficacy to treat pain. Evidence from work in our lab and others in preclinical animal models have shown that signaling from the bioactive sphingolipid, sphingosine-1-phosphate (S1P), through the S1P receptor subtype 1 (S1PR1) modulates neuro-immune cell interactions. Here, we discuss how targeting S1P/S1PR1 signaling with S1PR1 antagonists already Food and Drug Administration-approved or in clinical trials for multiple sclerosis can provide a viable pharmacotherapeutic approach to reduce neuro-immune cell inflammatory signaling and potentially treat patients suffering neuropathic pain and the adverse effects of opioids.

Topics: Analgesics, Opioid; Animals; Lysophospholipids; Neuralgia; Neuroinflammatory Diseases; Receptors, Lysosphingolipid; Sphingosine

FTY720 (fingolimod) is, after its phosphorylation by sphingosine kinase (SPHK) 2, a potent, non-selective sphingosine-1-phosphate (S1P) receptor agonist. FTY720 has been shown to reduce the nociceptive behavior in the paclitaxel model for chemotherapy-induced neuropathic pain through downregulation of S1P receptor 1 (S1P1) in microglia of the spinal cord. Here, we investigated the mechanisms underlying the antinociceptive effects of FTY720 in a model for trauma-induced neuropathic pain. We found that intrathecal administration of phosphorylated FTY720 (FTY720-P) decreased trauma-induced pain behavior in mice, while intraplantar administered FTY720-P had no effect. FTY720-P, but not FTY720, reduced the nociceptive behavior in SPHK2-deficient mice, suggesting the involvement of S1P receptors. Fittingly, intrathecal administration of antagonists for S1P1 or S1P3, W146 and Cay10444 respectively, abolished the antinociceptive effects of systemically administered FTY720, demonstrating that activation of both receptors in the spinal cord is necessary to induce antinociceptive effects by FTY720. Accordingly, intrathecal administration of S1P1 receptor agonists was not sufficient to evoke an antinociceptive effect. Taken together, the data show that, in contrast to its effects on chemotherapy-induced neuropathy, FTY720 reduces trauma-induced neuropathic pain by simultaneous activation of spinal S1P1 and S1P3 receptor subtypes.

Topics: Analgesics; Anilides; Animals; In Situ Hybridization; Lysophospholipids; Male; Mice; Neuralgia; Organophosphates; Organophosphonates; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Wounds and Injuries

The ceramide-sphingosine 1-phosphate (S1P) rheostat is important in regulating cell fate. Several chemotherapeutic agents, including paclitaxel (Taxol), involve pro-apoptotic ceramide in their anticancer effects. The ceramide-to-S1P pathway is also implicated in the development of pain, raising the intriguing possibility that these sphingolipids may contribute to chemotherapy- induced painful peripheral neuropathy, which can be a critical dose-limiting side effect of many widely used chemotherapeutic agents.We demonstrate that the development of paclitaxel-induced neuropathic pain was associated with ceramide and S1P formation in the spinal dorsal horn that corresponded with the engagement of S1P receptor subtype 1 (S1PR(1))- dependent neuroinflammatory processes as follows: activation of redox-sensitive transcription factors (NFκB) and MAPKs (ERK and p38) as well as enhanced formation of pro-inflammatory and neuroexcitatory cytokines (TNF-α and IL-1β). Intrathecal delivery of the S1PR1 antagonist W146 reduced these neuroinflammatory processes but increased IL-10 and IL-4, potent anti-inflammatory/ neuroprotective cytokines. Additionally, spinal W146 reversed established neuropathic pain. Noteworthy, systemic administration of the S1PR1 modulator FTY720 (Food and Drug Administration- approved for multiple sclerosis) attenuated the activation of these neuroinflammatory processes and abrogated neuropathic pain without altering anticancer properties of paclitaxel and with beneficial effects extended to oxaliplatin. Similar effects were observed with other structurally and chemically unrelated S1PR1 modulators (ponesimod and CYM-5442) and S1PR1 antagonists (NIBR-14/15) but not S1PR1 agonists (SEW2871). Our findings identify for the first time the S1P/S1PR1 axis as a promising molecular and therapeutic target in chemotherapy-induced painful peripheral neuropathy, establish a mechanistic insight into the biomolecular signaling pathways, and provide the rationale for the clinical evaluation of FTY720 in chronic pain patients.

Topics: Anilides; Animals; Antineoplastic Agents, Phytogenic; Cytokines; Enzyme Activation; Fingolimod Hydrochloride; Humans; Immunosuppressive Agents; Indans; Lysophospholipids; Male; Neuralgia; Organophosphonates; Oxadiazoles; Paclitaxel; Propylene Glycols; Rats; Rats, Sprague-Dawley; Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors; Thiazoles; Thiophenes